This is an NIH-funded study that has been underway at Mayo for approximately two years but was approved for use of the GCRC on June 18, 1999. The epidemiologic study seeks to determine the distribution of ventricular function parameters and the prevalence of ventricular systolic and diastolic dysfunction in a natural occurring population of adults. The study is also intended to determine whether plasma brain natriuretic peptide (BNP) can serve as an effective clinical marker for asymptomatic ventricular dysfunction.